Captive screw for thin panels

ABSTRACT

A captive screw device that includes a collar having a relatively thin wall at one end and an exterior shoulder at the other, the bore of the collar having a first cylindrical portion connecting to a second frustoconical portion, a screw extending through the collar with the undersurface of the head complementarily engageable with the surface of the collar at the second portion of the bore, the shank of the collar extending outwardly beyond the collar and receiving a washer, the shank having threads beyond the washer which have a larger major diameter than the opening through the washer for retaining the screw in the collar and preventing substantial relative axial movement, the thin-walled portion of the collar being bendable outwardly into a frustoconical recess to form a flange for securing the collar to a workpiece.

United States Patent 1 Gulistan July 31, 1973 Primary Examiner-Edward C.Allen Attorney-Richard F. Carr et al.

[57] g ABSTRACT A captive screw device that includes a collar having arelatively thin wall at one end and an exterior shoulder at the other,the bore of the collar having a first cylindrical portion connecting toa second frustoconical portion, a screw extending through the collarwith the undersurface of the head complementarily engageable with thesurface of the collar at the second portion of the bore, the shank ofthe collar extending outwardly beyond the collar and receiving a washer,the shank having threads beyond the washer which have a larger majordiameter than the opening through the washer for retaining the screw inthe collar and preventing substantial relative axial movement, thethin-walled portion of the collar being bendable outwardly into afrustoconical recess to form a flange for securing the collar to aworkpiece.

9 Claims, 4 Drawing Figures CAPTIVE SCREW FOR THIN PANELS [75] Inventor:Bulent Gulistan, Malibu, Calif. [73] Assignee: Deutsch Fastener Corp.,Los

Angeles, Calif.

[22] Filed: Aug. 26, 1971 [211 App]. No.: 175,056

52 us. or; 151/69 [51] Int. Cl. "L166 41120 [58] Field ofSearch15l/69,41.74; 292/251 [56] References Cited UNITED STATES PATENTS3,502,130 3/1970 Gulistan 151/69 2,470,927 5/1949 Hale 151/69 2,972,3672/1961 W0otton 151/69 2,360,274 10/1944 Rapp 151/69 2,709,470 5/1955Knohl 151/69 FOREIGN PATENTS OR APPLICATIONS 865,205 2/1941 France292/251 id W Patented July 31, 1973 ,144

INVENTOR. Z IG= 2 62/4 01/7 61/4 /5, MW

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionpertains to a captive screw.

2. Description of Prior Art In the fastener field, it is well recognizedthat captive screws offer many advantages for certain installations.With the screw permanently retained by the workpiece, it cannot becomelost when the fastener is in the separated position. Installation andremoval of parts is facilitated, with a saving of time and money. Inmany instances, it is desired to have the screw perform a jackingfunction to force the attached elements apart when the fastener isloosened. There have been various satisfactory designs for fasteners ofthese categories. However, such fasteners have not been applicable tothin panels. This is because it has not been possible to make the sleevethat retains the screw sufficiently short to permit a flange to beformed for retaining the sleeve to the workpiece, while at the same timeproviding the necessary bore through which the screw can extend. Also,the thin panels would not allow a conventional captive screw device tobe recessed adequately to provide a flush installation on the side ofthe panel where the head of the screw is located.

SUMMARY OF THE INVENTION The present invention provides a simplifiedcaptive screw which can be used successfully with thin panels. Thefastener is easily associated with the panel, so that it is heldsecurely and the panel is protected. The fastener can be made as ajacking screw to separate the components when the screw is loosened.Also, the installation of the fastener may be flush at the head end ofthe screw.

This is accomplished by a fastener that includes a collar having anexternal shoulderand a bore that is in two sections. One bore section iscylindrical, extending inwardly from one end, while the other isfrustoconical providing a converging wall that extends from the innerend of the cylindrical portion to the opposite end of the collar. Theend of the collar having the cylindrical bore is relatively thin-walledand bendable. A screw extends through the collar, the screw being of theflush-head type having a frustoconical undersurface that iscomplementary to the collar at the frustoconical portion of the bore.The head is received within the collar in a position where it isrecessed inwardly of the end of the collar. A shank extends from thehead beyond the frustoconical bore, with a washer being disposed on theshank. Rolled threads are formed on the shank outwardly of the washer,giving the threads a larger major diameter than the opening through thewasher so that the screw is retained by the collar. The threads mayextend to where their inner end is in juxtaposition with the washer,whereby the screw is prevented from substantial axial travel relative tothe collar. This enables it to accomplish a jacking effect.

When the fastener is attached to a workpiece, the external shoulder ofthe collar engages the workpiece on one side, while the thin-walled endis bent outwardly into a frustoconical recess on the opposite side ofthe workpiece. This holds the collar to the workpiece and provides aflush installation at the head end of the screw.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectionalview, partially inelevation, of the fastener of this invention;

FIG. 2 is a longitudinal sectional view of the fastener associated witha workpiece;

FIG. 3 is a longitudinal sectional view of'the' fastener attached to theworkpiece, with the screw of the'fastener engaging a mating part; and

FIG. 4 is a top plan view of the arrangementof FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fastener of this inventionincludes acollar 10, a screw 11 and a washer 12. The collar 10istubular'in configuration, initially made to have a'portion- 13 of aconstant exterior diameter extending from one end-14 to a radialshoulder 15 provided by the inner surface of a flange 16 of largerexterior diameter. Within the-collar 10, from an intermediate point tothe end 14, the bore section 17 is relatively wide and cylindrical. Thisprovides the collar with a relatively thin circumferential wall betweenthe bore 17 and the exterior portion 13. A frustoconical wall 18connects to the cylindrical portion 17 of the bore and extends tothe'opposite end 19 of the collar.

The screw 11 is of the flush-head type, the undersurface 20 of the head21 being frustoconical'and complementary to the frustoconical wallportion 18 of-the collar 10. The outside diameter of theouter end of thescrew head 21 is substantially equal to the-diameter of the bore section17. A suitabledriving slot- 22 of any desired configuration is formed inthe outer surface 23 of the screw head 21.

The shank 24 of the screw extends outwardly beyond the end 19 of thecollar 10. When the screw first is associated with the collar 10, theshank 24 is unthreaded. The washer 12 is fitted on the unthreaded shank24, the opening 25 of the washer being generally complementary to theshank. After the shank 24 has been extended through both the collar 10and the washer12, threads 26 are rolled on its exposed end. The threadrolling provides the threads with a larger major diameterthan that ofthe opening 25 of the washer 12. Consequently, the screw is retained bythe assembly of the collar 10 and the washer 12. The threads 26 willengage the washer to prevent removal of the screw in one direction,while the screw head 21 engaging the frustoconical surface 18 of thecollar prevents the screw from moving outwardly in the oppositedirection. When the fastener is to act as a jacking screw, in theembodiment illustrated, the threads 26 are formed to a position closelyadjacent the washer 12, with the screw head engaging the collar surface18. This means that substantial axial travel of the screw 1 1 relativeto the collar 12 is prevented.

The assembled fastener then is ready for attachment to a workpiece, suchas the thin panel 28 shown in FIGS. 2 and 3. The panel 28 is providedwith an opening 29 through it, which is substantially complementary tothe portion 13 of the exterior of the collar 10. A shallow frustoconicalrecess 30 is formed at one end of the opening 29 in the panel 28. Thefastener is associated with the panel 28 by extending the portion 13 ofthe collar through the opening 29 and bringing the shoulder 15 of thecollar into engagement with the surface 31 of the panel 28 opposite fromthe frustoconical recess 30. With the fastener held in this position,the thinwalled end of the collar is bent outwardly to form a flange 32,as seen in FIG. 4. A suitable tool 33 having a frustoconical surface 34at its end may be used to enter the thin-walled end of the collar andbend it outwardly into engagement with the frustoconical recess 30 inthe panel 28 to form the flange 32. When this is done, the flange 32cooperates with the shoulder in holding the fastener to the panel 28.The fastener installation is substantially flush at the upper side 35 ofthe panel 28 because the flange 32 is received in the frustoconicalrecess 30. The screw 11 becomes attached to the workpiece 28 in thismanner, where it is freely rotatable for providing a means forattachment to a mating part. However, with the threads being close tothe washer 12, substantial axial travel of the screw 11 relative to thepanel 28 is prevented.

The fastener can be used in attaching the panel 28 to any mating part,such as the adjoining element 36 shown in FIG. 4. The part 36 has athreaded opening 37 which receives the threads 26 of the shank of thescrew 11.

When the screw 11 is loosened, a jacking effect is realized which willpry the panel 28 relatively away from the part 36. This occurs becausethe screw 11 is prevented from substantial axial movement relative tothe panel 28 and, therefore, upon rotation in loosening its threads willproduce a reaction forcing the panel 28 from the part 36. The threads 26engage the washer 12 adjacent its bore 25 in transmitting the force thataccomplishes the separation of the parts. The washer 12 is made ofrelatively hard material, so that the threads 26 of the screw 11 willnot cut into it and will not act as a tap to produce new threads whichcould allow the screw to escape the collar. On the other hand, thecollar 10 is of a more soft and ductile material, which permits theflange 32 to be bent outwardly and firmly engage the recess 30 of thepanel 28 to securely hold the collar in place. The juncture of thefructoconical wall 18 and the flat radial end surface 19 results in asharp edge 38 on the relatively soft collar, which would be particularlysusceptible to having threads cut in it by the screw in the absence ofthe washer 12.

The washer 12 is a continuous annular member so that it is securely heldand will not become dislodged from the screw.

The foregoing detailed description is to be clearlyunderstood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

I claim:

1. A captive screw device comprising a collar,

said collar having an exterior shoulder facing one end thereof, and aninterior bore,

said bore including a first portion extending from an intermediateposition in said collar to said one end of said collar, said firstportion being defined by a first surface which is substantiallycylindrical, said bore including a second portion extending from anintermediate position in said collar to the other end of said collar,said second portion being defined by a second surface which issubstantially frustoconical,

a screw,

said screw having a head receivable in said collar, said head having afrustoconical undersurface engageable with said second surface of saidbore, said head having an outer surface which is spaced an appreciabledistance inwardly of said one end of said collar when said undersurfaceof said head engages said second surface of said bore, for therebyproviding a substantial length of said collar outwardly of said outersurface of said head, said screw including a shank extending outwardlybeyond said other end of said collar, and a washer on said shankadjacent said other end of said collar, said shank having threadsthereon outwardly of said washer, said threads having a larger majordiameter than the diameter of the opening through said washer, wherebysaid head and said threads prevent said screw from being removed fromsaid collar, said substantial length of said collar having a relativelythin wall such that it is adapted to be bent outwardly to fonn a flangefor cooperating with said exterior shoulder in holding said collar to aworkpiece.

2. A device as recited in claim 1 in which said washer is of relativelyhard material, and said collar is of relatively soft material comparedwith said washer, said collar being ductile for facilitating the outwardbending of said one end thereof for forming said flange.

3. A device as recited in claim 2 in which said other end of said collaris a flat surface substantially in a radial plane, whereby a sharp edgeis defined at the intersection of said second surface and said otherend, and said washer of relatively hard material can prevent saidthreads from engaging said sharp edge and cutting threads therein.

4. A device as recited in claim 2 in which said undersurface of saidhead is substantially complementary to said second surface of said bore.

5. A device as recited in claim 2 in which said threads extend inwardlyto a position such that, when said undersurface of said head is inengagement with said second surface of said bore, the inner end of saidthreads is in juxtaposition with said washer, whereby said screw isprevented from substantial axial movement relative to said collar.

6. In combination with a relatively thin workpiece having an openingtherethrough, said opening including a cylindrical portion extendinginwardly from one end thereof, and a frustoconical portion extendinginwardly from the opposite end thereof a captive screw device, saidcaptive screw device including a collar.

said collar including a portion having a cylindrical exterior receivedin said cylindrical portion of said opening,

said collar including an annular exterior shoulder adjacent one endthereof engaging the surface of said workpiece adjacent said one end ofsaid opening.

said collar including an outwardly bent flange at the opposite endthereof substantially complementarily engaging said frustoconicalportion of said opening, said collar having a bore including acylindrical portion inwardly of said flange and a frustoconical portionconnected to said cylindrical portion and converging away therefrom, ascrew extending through said collar,

said screw having a head,

said head having an outer surface having a recess therein for rotatingsaid screw relative to said workpiece and a frustoconical undersurfaceengageable with the surface of said frustoconical portion of said bore,said outer surface of said head being positioned axially inwardly of thebase of said flange of said collar when said undersurface of said headengages said frustoconical portion of said'bore, said screw having ashank extending outwardly from said one end of said collar, and a washeron said' shank,

said shank having threads thereon outwardly of said washer, said threadshaving a larger major diameter than the diameter of the opening throughsaid washer, whereby said head and said threads prevent said washer fromseparation from said collar.

7. A device as recited in claim 6 in which said frustoconical portion ofsaid bore extends to said one end of said collar.

8. A device as recited in claim 6 in which, when said undersurface ofsaid head engages said surface of said frustoconical portion of saidbore, said threads are in juxtaposition with said washer, whereby saidscrew is prevented from substantial axial movement relative to saidcollar.

9. A device as recited in claim 6 in which said flange does not extendsubstantially beyond the surface of said workpiece at said opposite endof said opening, whereby said captive screw-device provides asubstantially flush installation at said one end of said opening. 1' l il

1. A captive screw device comprising a collar, said collar having anexterior shoulder facing one end thereof, and an interior bore, saidbore including a first portion extending from an intermediate positionin said collar to said one end of said collar, said first portion beingdefined by a first surface which is substantially cylindrical, said boreincluding a second portion extending from an intermediate position insaid collar to the other end of said collar, said second portion beingdefined by a second surface which is substantially frustoconical, ascrew, said screw having a head receivable in said collar, said headhaving a frustoconical undersurface engageable with said second surfaceof said bore, said head having an outer surface which is spaced anappreciable distance inwardly of said one end of said collar when saidundersurface of said head engages said second surface of said bore, forthereby providing a substantial length of said collar outwardly of saidouter surface of said head, said screw including a shank extendingoutwardly beyond said other end of said collar, and a washer on saidshank adjacent said other end of said collar, said shank having threadsthereon outwardly of said washer, said threads having a larger majordiameter than the diameter of the opening through said washer, wherebysaid head and said threads prevent sAid screw from being removed fromsaid collar, said substantial length of said collar having a relativelythin wall such that it is adapted to be bent outwardly to form a flangefor cooperating with said exterior shoulder in holding said collar to aworkpiece.
 2. A device as recited in claim 1 in which said washer is ofrelatively hard material, and said collar is of relatively soft materialcompared with said washer, said collar being ductile for facilitatingthe outward bending of said one end thereof for forming said flange. 3.A device as recited in claim 2 in which said other end of said collar isa flat surface substantially in a radial plane, whereby a sharp edge isdefined at the intersection of said second surface and said other end,and said washer of relatively hard material can prevent said threadsfrom engaging said sharp edge and cutting threads therein.
 4. A deviceas recited in claim 2 in which said undersurface of said head issubstantially complementary to said second surface of said bore.
 5. Adevice as recited in claim 2 in which said threads extend inwardly to aposition such that, when said undersurface of said head is in engagementwith said second surface of said bore, the inner end of said threads isin juxtaposition with said washer, whereby said screw is prevented fromsubstantial axial movement relative to said collar.
 6. In combinationwith a relatively thin workpiece having an opening therethrough, saidopening including a cylindrical portion extending inwardly from one endthereof, and a frustoconical portion extending inwardly from theopposite end thereof, a captive screw device, said captive screw deviceincluding a collar, said collar including a portion having a cylindricalexterior received in said cylindrical portion of said opening, saidcollar including an annular exterior shoulder adjacent one end thereofengaging the surface of said workpiece adjacent said one end of saidopening. said collar including an outwardly bent flange at the oppositeend thereof substantially complementarily engaging said frustoconicalportion of said opening, said collar having a bore including acylindrical portion inwardly of said flange and a frustoconical portionconnected to said cylindrical portion and converging away therefrom, ascrew extending through said collar, said screw having a head, said headhaving an outer surface having a recess therein for rotating said screwrelative to said workpiece and a frustoconical undersurface engageablewith the surface of said frustoconical portion of said bore, said outersurface of said head being positioned axially inwardly of the base ofsaid flange of said collar when said undersurface of said head engagessaid frustoconical portion of said bore, said screw having a shankextending outwardly from said one end of said collar, and a washer onsaid shank, said shank having threads thereon outwardly of said washer,said threads having a larger major diameter than the diameter of theopening through said washer, whereby said head and said threads preventsaid washer from separation from said collar.
 7. A device as recited inclaim 6 in which said frustoconical portion of said bore extends to saidone end of said collar.
 8. A device as recited in claim 6 in which, whensaid undersurface of said head engages said surface of saidfrustoconical portion of said bore, said threads are in juxtapositionwith said washer, whereby said screw is prevented from substantial axialmovement relative to said collar.
 9. A device as recited in claim 6 inwhich said flange does not extend substantially beyond the surface ofsaid workpiece at said opposite end of said opening, whereby saidcaptive screw device provides a substantially flush installation at saidone end of said opening.